JPH0596813U - Optical member driving device - Google Patents

Abstract

(57) [Summary] [Object] To provide a lens drive device that does not require a spring for urging a cam follower, has high accuracy, can be downsized, and is easy to assemble. In a lens driving device for driving a lens by a cam groove and a cam follower, the cam follower 9 itself is provided with at least a pair of leaf portions 9a, 9b which are elastic portions for exerting an elastic force substantially along the lens optical axis direction, It is characterized in that the pair of elastic portions are press-fitted and fitted into the side surfaces of the cam groove so that the center of the cam follower 9 moves on the target trajectory of the cam groove.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an optical-related member driving device, and more particularly, to a structure of a cam follower in an optical-related member driving device that drives an optical-related member by a cam and a cam follower.

[0002]

[Prior Art]

 Conventionally, a mechanism using a cam and a cam follower is generally used in an optical-related member driving device that is installed in a camera or the like, for example, an optical-related member driving device that drives a zoom lens, a focusing lens, or the like to move back and forth. ing. In recent years, along with the computerization of the main body device, there has been developed a device in which a small displacement error of the forward / backward movement position of the lens or the like affects the optical performance thereof. Therefore, in the optical-related member driving device, it is required in the future that the driving device has higher precision and smaller size, lighter weight and lower cost.

Therefore, the structure of a conventional example of a lens driving device, which is the above-mentioned optical-related member driving device, will be described. The lens driving device shown in the perspective view of FIG. 8 is composed of two groups of lenses for zooming. The lens holding frame is driven via the cam groove and cam follower. In the apparatus, the lenses 21 and 22 of the above-mentioned two-group structure which are optical-related members are respectively held by lens holding frames 23 and 24, and the lens holding frames 23 and 24 are respectively attached to the boss portions 23a and 24a. It is supported by guide shafts 27 and 28 so as to be movable back and forth in the optical axis O direction through the shaft hole and the notches in the forked portions 23b and 24b. An image sensor holder 26 for holding the image sensor 25 is fixed to the ends of the guide shafts 27 and 28.

Further, cam followers 29 and 29 ′ having a circular cross section are fixed below the boss portions 23 a and 24 a, respectively. The cam followers 29 and 29 'are members having the same shape, and are slidably fitted in the cam grooves 30a and 30b provided in the cam plate 30. In the above device, the cam groove is provided on a disc-shaped cam plate rotatably supported by the shaft 31, but in addition to this, the cam groove is formed on a rotatable cam ring having a cylindrical shape. A drive device provided with is also generally used.

By rotating the cam plate 30 by a predetermined angle, the cam followers 29, 29 ′ are driven to move the lens holding frames 23, 24 forward and backward in the optical axis direction. In order to maintain the slidable state, the cam followers 29, 29 'are slightly smaller than the width W of the cam grooves 30a, 30b from the viewpoint of accuracy of parts and temperature difference during operation, as shown in FIG. For example, a diameter D that is smaller by a dimension on the order of 1/100 mm is given. Therefore, the fitting backlash d inevitably occurs. This backlash appears as an error in the advance / retreat position of the lens holding frames 23, 24. Therefore, in order to eliminate the fitting backlash, in this device, the springs 32 and 33 are suspended on the boss portions 23a and 24a of the lens holding frames 23 and 24 to urge the lens holding frames 23 and 24 in a predetermined direction. To do. Then, the cam followers 29, 29 'are brought into contact with the reference surfaces of the cam grooves 30a, 30b to remove the play. FIG. 10 shows a state in which the cam followers 29, 29 'are in contact with the cam reference surface by the urging force F of the springs 32, 33.

However, in the above-described conventional apparatus, the springs 32 and 33 for urging the cams must be arranged around the lens holders 23 and 24, which causes a space problem. Further, the rotational load of the cam plate 30 varies depending on the forward and backward positions of the lens holding frames 23 and 24, which is not preferable in terms of motor driving characteristics. Furthermore, the man-hours for suspending the spring were also required.

Therefore, as a proposal for solving these problems, there is a lens moving mechanism using a cam groove disclosed in Japanese Patent Laid-Open No. 54-91322. In the mechanism of this proposal, as shown in FIG. 11 as an example of the shape of the cam follower of the lens holding frame, by inserting a slit into the cam groove fitting portion of the cam follower 49, the large cross section portion 49a having a large thickness and the thick cross section portion A thin elastically deformable small cross section 49b is formed. However, the outer dimension D'between the cross sections 49a and 49b is set to be slightly larger than the width W of the cam groove 30a. The cam follower 49 is fitted in the cam groove 30a. At the time of fitting, the small cross section 49b is deformed in the direction of the optical axis O and press-fitted (see FIG. 12).

In the lens moving device configured as described above, the cam follower 49a can slide on the cam groove 30a without backlash when the lens holding frame is moved back and forth, and the lens holding frame is not affected by backlash. It is possible to drive the vehicle back and forth. Further, it is not necessary to dispose the springs 32 and 33 as in the lens driving device of FIG. 8, and the device can be downsized.

[0009]

[Problems to be solved by the device]

 However, in the lens movement mechanism using the cam groove disclosed in Japanese Patent Laid-Open No. 54-91322, when the cam follower 49a is press-fitted into the cam groove 30a, only the small cross section 49b is deformed. Therefore, the center position of the cam follower 49 and the center of the cam groove 30a do not necessarily coincide with each other due to variations in the groove width and the size of the cam follower. FIG. 13 is a plan view showing a sliding state with respect to the cam groove 30a in the engaged state. Actually, the cam plate 30 rotates and the cam follower 49 fixed to the lens holding frame moves back and forth only in the optical axis O direction. However, in FIG. 13, the cam plate 30 is fixed. The cam follower 49 has moved to a tele position 49 (A) on the optical axis OT, a standard position 49 (B) on the optical axis OS, and a wide position 49 (C) on the optical axis OW, respectively. Is shown as. As shown in the figure, the cam groove 30a is formed along the locus of the outer diameter C of the cutter 12. The locus of the center line L1 of the cutter 12 becomes the locus of the center of the cam follower according to the design specifications.

However, since the large cross section 49a actually contacts and slides on the reference surface side of the cam groove 30a, the center line of the cam follower passes through the locus L2. The locus L2 and the center line L1 of the cutter 12 are deviated from the optical axis OT by the machining width error of the cutter 12 and the external dimension error of the cam follower 49. There is a possibility of causing deviation eW on OW. Therefore, the advancing / retreating position of the taking lens is different from the designed advancing / retreating position, and it becomes difficult to satisfy the design specifications. When the cam plate 30 is a molded part, the error in the working width of the outer diameter C of the cutter 12 corresponds to the variation in the product size of the molded product.

The present invention was made in order to solve the above-mentioned inconvenience, and a pair of elastic forces are exerted on the cam follower itself along substantially the optical axis direction of the optically related member, so that the center of the cam follower acts as a cam. An optical-related member that is configured to move on the target orbit without rattling, does not require a spring for urging the cam follower, has high accuracy, can be downsized, and is easy to assemble. An object is to provide a drive device.

[0012]

[Means for Solving the Problems]

 The optical related member driving device of the present invention is an optical related member driving device for driving an optical related member by a cam and a cam follower, wherein at least one pair of elastic force is exerted on the cam follower itself along substantially the optical axis direction of the optical related member. An elastic portion is provided, and the pair of elastic portions are engaged with the side surfaces of the cam groove so that the center of the cam follower moves on the target trajectory of the cam groove.

[0013]

[Action]

 With the pair of elastic portions of the cam follower engaged with the side surfaces of the cam groove, the cam groove or the cam follower is relatively moved to move the cam follower forward and backward. At that time, the center of the cam follower moves on the target orbit of the cam groove.

[0014]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of a lens driving device which is an optical member driving device according to an embodiment of the present invention. The apparatus of the present embodiment is an optical member that drives the lens holding frame of the two-group lens for zooming through the cam groove through the cam follower. The configuration other than the cam follower is the same as that shown in FIG. It has the same configuration as the conventional lens driving device shown.

As shown in FIG. 1, the cam followers 9 and 9 ′ are fixed below the boss portions 23 a and 24 a of the lens holding frames 23 and 24 that hold the lenses 21 and 22 that are optical members, respectively. To be done. The cam followers 9, 9'are members having the same shape, and are slidably fitted in cam grooves 10a, 10b provided in a cam plate 10 which is rotatably supported by a shaft 11. However, as shown in the perspective view of FIG. 2, the cam followers 9 and 9'are divided into three parts, that is, the central part 9a and the leaf parts 9b and 9c, by the two parallel slits on the sides fitted into the cam grooves 10a and 10b. Has been. The central portion 9a forms a rigid body portion, and the leaf portions 9b and 9c form a pair of elastic portions that are elastically deformable in the direction orthogonal to the slotting direction, that is, in the optical axis O direction in the mounted state. The outer dimension D1 in the elastically deforming direction is slightly larger than the width W of the cam grooves 10a, 10b by a press-fitting margin 2.S (see FIG. 3).

FIG. 3 is a view showing a deformed state when the cam followers 9, 9 ′ are press-fitted into the cam grooves 10 a, 10 b. As shown in the figure, the leaf portions 9b and 9c of the cam followers 9 and 9'are respectively deformed by the dimension S and press-fitted into the cam grooves 10a and 10b having the groove width W. The outer shape of each of the leaf portions 9b and 9c has an arc shape having a radius of 1/2 of the cam groove width W.

Then, the cam followers 9, 9 ′ are held in a state of being fixed to the lens holding frames 23, 24 in a direction in which the slitting direction is orthogonal to the optical axis O direction. Then, as shown in the plan view of the cam groove fitting state of FIG. 4, the cam plates 10 are press-fitted and fitted into the side surfaces of the cam grooves 10a and 10b. As a method of press-fitting the cam plate 10, the cam plate 10 is rotated clockwise, and the wide relief portions 10c and 10d provided in the leaf portion of the cam groove are positioned on the optical axis O. Then, the cam followers 9, 9'are once inserted into the escape portions 10c, 10d. After that, when the cam plate 10 is rotated counterclockwise, the cam followers 9 and 9'become in the press-fitted state and the lens frame drive state as shown in FIG.

In the lens driving device of the present embodiment configured as described above, assuming that the state shown in FIG. 4 is the standard state of zooming, from this state, the cam plate 10 is moved in the T direction or W When rotated in the direction, the cam followers 9, 9'are driven in the optical axis O direction by the cam grooves 10a, 10b without play. Then, the lens holding frames 23 and 24 move to the tele position or the wide position along the guide shafts 27 and 28, respectively.

FIG. 5 is a diagram showing an operating state of the cam follower 9 with respect to the cam groove 10a at that time. Since the same applies to the cam follower 9 ', only the cam follower 9 will be described here. As described above with reference to FIG. 13, the cam plate 10 actually rotates and the cam follower 9 fixed to the lens holding frame moves back and forth only in the optical axis O direction. In FIG. 5, the cam plate 10 is shown fixed, and the cam follower 9 has a tele position 9 (A) on the optical axis OT, a standard position 9 (B) on the optical axis OS, and a wide position 9 on the optical axis OW. It is shown as having moved to (C). As shown in this figure, the cam groove 10a is formed by the locus of the outer diameter C of the cutter 12, and the locus of the center line L1 of the cutter 12 is the locus of the center of the cam follower in the design specifications as in the case of FIG. Become.

In the present embodiment, since the elastic deformation dimension S (see FIG. 4) of the leaf portions 9b and 9c due to the press-fitting engagement of the cam follower 9 is substantially the same, the telescopic movement of the cam follower 9 The center points PT, PS and PW at the standard and wide positions pass through the center line L1 of the cutter 12. Therefore, the advance / retreat position of the lens coincides with the designed advance / retreat position, and the lens drive satisfying the design specifications can be executed without play.

Further, according to the lens driving device of the present embodiment, it is not necessary to dispose a spring for removing backlash around the lens holding frame, which is used in the conventional example, so that the number of parts and the number of assembling steps can be reduced. At the same time, the space for arranging the spring is not required, and the size can be reduced. Furthermore, since the cam drive load does not change much with respect to the lens drive position, the drive motor load is stabilized. When an impact force is applied to the lens holding frames 23 and 24 by the present lens driving device, the leaf portions 9a and 9c of the cam follower 9 are deformed to absorb the impact force, and are deformed by a predetermined amount or more. At this time, since the cam follower 9 acts as a rigid body, it has high impact resistance against a drop or the like.

Next, a modified example of the cam follower used in the lens driving device of the above embodiment will be described. FIG. 6 is a perspective view showing the shape of the cam follower of the modified example. The cam follower 15 is formed of a leaf spring or an elastic body such as a rubber member around the central rigid body portion 15b, and is in the G direction. The leaf portion 15a, which is an elastic portion that can be elastically deformed, is fixedly formed. The other drive mechanism parts of the drive device to which the cam follower 15 is applied are the same as those in the above embodiment. Also in the case of this modification, the cam follower 15 is mounted in the lens holding frame so that the G direction is aligned with the optical axis O direction. Further, in this modification, since the rigidity of the elastic deformation of the leaf portion 15a can be set to a comparatively arbitrary value, the fluctuation of the driving load is reduced and the elastic deformation dimension is also stabilized, so that it is possible to achieve higher accuracy. Cam drive can be performed.

Next, another modified example of the cam follower used in the lens driving device of the above embodiment will be described. FIG. 7 is a perspective view showing the shape of the cam follower of the modified example. The cam follower 16 is provided with chamfered portions 16e and 16f on the end surfaces of the leaf portions 16b and 16c, which are elastic portions, on the cam groove insertion side. Similarly, the central portion 16a, which is a rigid portion, is also provided with a chamfered portion 16d on the end surface on the cam groove insertion side. However, the diameter of the tip of each of the chamfered portions 16d, 16e, 16f is smaller than the width of the cam groove. Further, the height of the central portion 16a is set lower than that of the leaf portions 16b and 16c so that the leaf portions 16b and 16c can be easily fitted into the cam groove. However, lowering the height of the central portion 16a facilitates insertion, and does not necessarily have to be set low. The structure of the other drive mechanism portion of the drive device to which the cam follower 16 is applied is the same as that of the above embodiment. In this modification, the cam follower 16 is fitted into the cam groove by being guided by the chamfered portions 16e, 16f and 16d and fitted into the cam groove, so that the cam follower 16 can be easily assembled. Then, the escape portions 10c and 10d of the cam groove for inserting the cam follower shown in the above embodiment are not necessary.

[0024]

[Effect of the device]

 As described above, in the optical member driving device of the present invention, the cam follower is provided with a pair of elastic portions that are elastically deformable in the optical axis direction, and the forward and backward movement is performed with the elastic portions engaged with the side surfaces of the cam groove. Since the center of the cam follower is moved with high precision without rattling along the target track of the cam groove, it is necessary to install the spring for rattling used in the conventional example. In addition, the number of parts and the number of assembling steps can be reduced, and at the same time, the space for arranging the spring is not required, which enables downsizing of the device and increases the degree of freedom in design. Furthermore, the cam drive load has a small variation with respect to the change of the drive position, and the drive motor can be easily selected.

[Brief description of drawings]

FIG. 1 is a perspective view of a driving mechanism portion of a lens driving device that is an optical member driving device according to an embodiment of the present invention.

FIG. 2 is a perspective view of a cam follower used in the lens driving device of FIG.

FIG. 3 is a view showing a deformed state when a cam follower is fitted into a cam groove of the lens driving device of FIG.

FIG. 4 is a plan view showing an assembled state of a cam follower and a cam groove of the lens driving device of FIG.

FIG. 5 is a view showing an operating state of a cam follower on a cam groove at the time of tele, standard, and wide of the lens driving device of FIG. 1;

6 is a perspective view of a modification of the cam follower of the lens driving device of the embodiment of FIG.

FIG. 7 is a perspective view of another modified example of the cam follower of the lens driving device of the embodiment of FIG.

FIG. 8 is a perspective view of a driving mechanism portion of a lens driving device showing a conventional example.

FIG. 9 is a view showing a fitted state in which there is looseness in a cam groove and a cam follower in the lens driving device of FIG. 8;

10 is a view showing a state in which a cam follower is biased by a spring and fitted into a cam groove in the lens driving device of FIG. 8;

FIG. 11 is a perspective view of a cam follower used in a lens driving device showing another conventional example.

12 is a view showing a fitted state of a cam groove and a cam follower in the lens driving device of FIG.

FIG. 13 is a telephoto, standard, of the lens driving device of FIG.
The figure which shows the operation state of the cam follower on a cam groove at the time of wide.

[Explanation of symbols]

9,9 ', 15,16 …………………… Cam followers 10a, 10b …………… Cam grooves (cams, cam groove side surfaces) 9a, 9b, 15a, 16b, 16c ……… Leaf Part (a pair of elastic parts) 23, 24 …………………… Lens holding frame (optical related member) O ……………… Optical axis

Claims (1)

[Scope of utility model registration request] 1. An optical-related member drive device for driving an optical-related member by a cam and a cam follower, wherein the cam follower itself is provided with at least a pair of elastic portions for exerting an elastic force along substantially the optical axis direction of the optical-related member, An optical-related member driving device, characterized in that the pair of elastic portions are engaged with the side surfaces of the cam groove so that the center of the cam follower moves on a target trajectory of the cam groove.